At present, most rivers are crossed by crucian carp and red carp. Carassius auratus is a natural triploid, and the egg development does not go through the second meiosis, so the egg is also triploid. Fertilization of crucian carp eggs only needs sperm stimulation (crucian carp can use it), but it will not fuse (it will exchange some genes). 98% of the offspring are females, and there are few males, so it is normal not to catch males.

Female identification method: fish breeding season (3 to

About June) Male fish will have a lot of Zhu Xing or idolization (the second sexual characteristic of fish, similar to a man's beard), while female fish are rare. The male fish will cut his hand when he gently touches the pectoral fin of the fish, and he will see many protruding things with his eyes, such as sawtooth. There are no or few women.